Dynamical behaviors of structural, constrained and free water in calcium- and magnesium-silicate-hydrate gels

Journal Article · Thu Jan 28 00:00:00 EST 2016 · Journal of Colloid and Interface Science

DOI:https://doi.org/10.1016/j.jcis.2016.01.071· OSTI ID:1261396

Le, Peisi  ^[1]; Fratini, Emiliano ^[2]; Ito, Kanae ^[1]; Wang, Zhe ^[1]; Mamontov, Eugene ^[3]; Baglioni, Piero  ^[2]; Chen, Sow-Hsin ^[1]

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1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Nuclear Science and Engineering
2. Univ. of Florence (Italy). Dept. of Chemistry "Ugo Schiff" and CSGI
3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)

We present the hypothesis that the mechanical properties of cement pastes depend strongly on their porosities. In a saturated paste, the porosity links to the free water volume after hydration. Structural water, constrained water, and free water have different dynamical behavior. Hence, it should be possible to extract information on pore system by exploiting the water dynamics. With our experiments we investigated the slow dynamics of hydration water confined in calcium- and magnesium-silicate-hydrate (C-S-H and M-S-H) gels using high-resolution quasi-elastic neutron scattering (QENS) technique. C-S-H and M-S-H are the chemical binders present in calcium rich and magnesium rich cements. We measured three M-S-H samples: pure M-S-H, M-S-H with aluminum-silicate nanotubes (ASN), and M-S-H with carboxyl group functionalized ASN (ASN-COOH). A C-S-H sample with the same water content (i.e. 0.3) is also studied for comparison. We found that structural water in the gels contributes to the elastic component of the QENS spectrum, while constrained water and free water contribute the quasi-elastic component. The quantitative analysis suggests that the three components vary for different samples and indicate the variance in the system porosity, which controls the mechanical properties of cement pastes.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC05-00OR22725; FG02- 90ER45429; FG02-90ER45429
• OSTI ID: 1261396
• Alternate ID(s): OSTI ID: 1346258
• Journal Information: Journal of Colloid and Interface Science, Vol. 469, Issue C; ISSN 0021-9797
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
Water dynamics
Porous material
Quasi-elastic neutron scattering
Calcium-silicate-hydrate
Magnesium-silicate-hydrate